Many problems with known ash-like material loading systems have been encountered. First, the loading operation is often excessively dusty causing health concerns for workers inhaling the airborne particulate matter. Dry ash-like material is often on top of the slump (or pile of material) in the truck 170 and blows or drops from the truck 170 onto the plant property or highways. Further, because of gravity and over saturation with liquid, the bottom of the slump becomes wet or sticky during travel on a truck, causing an unloading hazard and an ash-like material water slurry 5 that leaks from the truck onto the plant property or onto public highways (see FIG. 3). The effects of this leakage leave an alkaline material that is generally between 0.2 inches and 3 inches thick on surfaces (see FIG. 3). Further, current operators cannot control the process because of the varying conditions of the material as it falls.
Also, in known systems, truck drivers do not know when to respond to the loading process without leaving the cab and putting themselves at risk of either inhaling airborne particulate matter or slipping on spilled material. Plants generally do not want drivers out of their vehicles during loading for safety reasons. FIG. 2 shows an example of a driver viewing slump progression in a known system.
Trucks 170 are frequently overloaded (see FIG. 1) or under loaded because the known systems are blind to the loading status of each slump. Overloading causes massive amounts of ash material 175 to fall onto the loading dock floor (see FIG. 1). When overloading or under loading occurs, the truck loads are adjusted at the plant site by an excavator or similar machine. Generally, about one out of every five loads must be adjusted before the truck is released for the road. The excavator either adds or takes away material. This process is quite costly for the plant in that it must have an excavator or similar machine on-site to accomplish the load adjustment. The company must also pay the excavator operators. Additionally, after load adjustment, the driver must reweigh, again costing time and money. The system of the present invention eliminates the need for the excavator and load adjustment process by optimal filling.
Further, in known ash conditioning systems, the water or liquid flow rate is held constant or manually controlled by the operator, while the ash flow rate varies, so the ash condition is not consistent, causing diverse water or liquid concentrations in the ash. The ash flow rate varies even when the operator is using a feeder or control valve. Water flow is not measured in known systems. Therefore, an operator frequently over saturates the ash material to avoid the visual appearance of airborne particulate in the loading bay. These known conditioning systems assume that a constant ash flow is provided through the loading chute, which is not technically accurate in most situations.
Currently, the ash empties from the silo through two valves. The valve closest to the silo is on-off (open-shut) valve, while the other valve is a control valve that is set at a static percent open position by the operator. The ash flows through this valve system into a pug mill where a constant flow of water is applied to the ash. The valve system and the pug mill are controlled on an on/off and timeout basis that is initiated by the tug of a rope located near the ash chute. Alternatively, an operator can run the process by sight or video without the rope.
When the truck is positioned under the chute, the driver or operator tugs on the rope or operates the system to allow ash to enter the pug mill and fall into the chute that leads to the truck bed. Another tug on the rope stops the pug mill input and allows the ash charge to flush through the pug mill and chute on a timeout basis. The entire process lasts for about three and a half minutes and loads about 22 tons of water and ash into the truck bed at close to a maximum rate of 400 tons per hour.
The known process further does not ensure a consistent water to ash ratio throughout the load or individual slumps as the flow of the ash constantly varies. This situation generates physically irritating dust at the plant site or on the roadways because the ratio of water to ash is too low. When the ratio is too high, ash/water slurry 5 commonly leaks from the truck 170 causing dirty conditions in the plant area as well as the need to remove the build-up from the roadways (see FIG. 3). In addition, excessively wet ash tends to stick to the truck's 170 bed, increasing the risk of truck rollover during the dumping operation.
The present invention overcomes the many disadvantages of the known systems as discussed below.